Azo dyes as filters in color photography



Nov. 18, 1958 J, M, STRALEY 2,860,979

AZO DYES AS FILTERS IN COLOR PHOTOGRAPHY Filed April 26, 1955 BLUE '-$E NS/ 77 VE EMULSION REEN-SE/VS/T/VE EMULSION REp-sms/r/l E EMULSION //F1.SUPP0RT PHOTOGRA PH/C EMULSION SUPPORT AZ 0 DYE JAMES M. STRALEY IN VEN TOR.

A TTORIVE YS United States Patent Ow lce AZO DYES AS FILTERS IN COLOR PHOTOGRAPHY James M. Straley, Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation or New Jersey Application April 26, 1955, Serial No. 503,877

8 Claims. (Cl. 96-84) The present invention relates to improved photographic elements, and more particularly, to photographic elements having light-screening substances therein.

It is known that photographic elements require, for many purposes, light-screening substanes incorporated therein. Such a light-screening substance can be in a layer overlying a light-sensitive emulsion or two or more such light-sensitive emulsions, or it can be incorporated in the light-sensitive emulsion layer itself for the purpose of modifying a light record in such emulsion, or protecting an underlying light-sensitive emulsion or emulsions from the action of light of wave-length absorbed by such light-screening substances. Alternatively, such lightscreening substances can be in a layer not containing a light-sensitive substance, but arranged between two lightsensitive emulsions, or such light-screening substances can be in a layer serving as a backing on an element having one or more light-sensitive emulsions for the purpose of reducing halation.

More particularly, such light-screening substances are required in layers arranged between differentially-colored sensitized emulsions, e. g., to protect the red and green sensitized emulsions from the action of blue light, or in backings forming the so-called anti-halation layers on either side of a transparent support carrying the lightsensitive emulsion or emulsions.

In most cases, and particularly where the photographic element contains differentially-colored sensitized emulsions (or color-sensitized emulsions), it is desirable to' employ light-screening substances which do not affect the general sensitivity or the color sensitivity of the lightsensitive emulsions with which they may come into contact, and in addition to have the, desirable property of easy removal from the photographic element after or during development of the exposed photographic element. 7 Such light-screening substances which do not undergo substantial diflusion from the layers or coatings in which they are incorporated, either during the manufacture of the photographic element or on keeping 'it in a photographic processing solution, are especially useful.

In general, such light-screening substances should be easily removed or made ineffective by one of the processing solutions customarily employed in photographic treatments, e. g., a photographic developing bath, fixing bath, or a silver-oxidizing (including silver-removing) bath. Such removal or rendering ineffective is particularly important when making color photographs using several differentially color-sensitized emulsions containing the usual silver halide salts. Such differentially color-sensitized emulsions must be processed to diiferent colors and to facilitate diflerential colorprocessing, methods involving selectiveexposure of light-sensitive images in the layers can be employed. Such selective re-exposure, e. g., of silver halide remaining undeveloped in development of the latent images formed in silver halide emulsion layers is often facilitated, if the light-screening substance ized or removed during treatment in one of the processing granted August 16, 1938.

stituted thereon a carboxyl radical, a sulfo radical, or a The instant invention relates to the use of a new type of light-screening dye which is easily removed during the photographic processing customarily employed. The dyes of my invention form stable filter coatings and cause little or no'desensitizing in photographic emulsions with which they come in contact.

Accordingly, it is an object of my invention to provide new photographic elements. A further object of my invention is to provide photographic elements differentiallysensitized for use in photographic color processes and containing a particular type of light-screening substance. Still another object of my invention is to provide new light-screening dyes and a method for making them. Other objects will become apparent from a consideration of the following description and examples.

The light-screening dyes which I advantageously employ in practicing my invention can be represented by the following general formula:

H 5 RN=N oH wherein R represents an aryl group, such as phenyl,

naphthyl, etc. Alternatively, the dyes represented by,

Formula I above can be written according to the followwherein R has the values given above.

Light-screening dyes which I have found to be particularly useful in practicing my invention comprise the dyes of Formula II (or I) wherein the group R has subsalt (e. g., alkali metal salt, organic amine salt, etc.) of said radicals. Another group of dyes embraced by Formula H above which can advantageously be employed in practicing my invention are those dyes represented by which was present during the original exposure is decolorthe following general formula:

wherein R and R each represents a hydrogen atom, a

halogen atom (e. g., chlorine, bromine, etc.), a nitro group, a cyano group, a sulfonamido group, a hydroxyl group, an alkoxyl group (e. g., methoxyl, ethoxyl, etc.), an aryloxyl group (e. g., phenoxyl, methylphenoxyl, etc.), an aryl group (e. g., phenyl, 0-, mand p-tolyl, etc.),

an alkyl group (e. g., methyl, ethyl, n-propyl, etc.), an

Patented Nov. 18 19 58v wherein R and R each have the values given above. While the mixture can be heated somewhat to facilitate the desired reaction, it is generally not necessary to do so, and room temperatures, or temperatures below room temperature, can advantageously be employed. The diazonium salts of the amines represented by Formula IV above can be prepared in the known manner, from a mixture of sodium nitrite and hydrochloric acid. The method of preparing compounds selected from those represented by Formulas II and III above is further described in Jour. Am. Chem. Soc., vol. 77 (1955), pages 403- 405.

In the accompanying drawing, the figures are enlarged sectional views of photographic elements illustrative of my invention, showing filter or anti-halation layers in representative elements.

Among the light-screening dyes selected from those represented by Formulas II (or I) and IH which can be used in practicing my invention are those represented by the following formulas:

HNSOsCuHMn) O The aromatic amines represented by Formula IV above required for the preparation of the light-screening dyes of my invention can be prepared as described in Sprung U. S. Patent 2,629,658, issued February 24, 1953. Many of these amines are old substances and having been described elsewhere. Where the light-screening dyes of my invention are water-soluble, they can be incorporated in the photographic layer by simply preparing stock solutions of the dye and adding these photographic solutions to an aqueous solution or suspension of the conventional water-permeable colloids employed in photographic coatings such as gelatin, polyvinyl alcohol, starch, agar-agar, gum arabic, hydrolyzed cellulose acetate, hydroxymethyl cellulose, etc. Where the filter dye is not soluble in water, it can be dissolved in one of the usual organic solvents, such as pyridine, ethanol, etc., and added to the waterpermeable colloid in this condition.

The following examples will serve to illustrate the manner whereby I practice my invention.

Example 1 Five g. of sulfanilic acid were dissolved in 25 cc. of water containing 2.5 g. KOH. The solution was cooled to 5 C. and a solution of 2.0 g. NaNO in 20 cc. of water added, followed by addition beneath the surface of a chilled solution of 4 cc. of water and 8 cc. of concen trated HCl at 57 C. After addition, the solid diazonium salt was filtered off and added to a solution of 3.65 g. of B-methylglutaconic anhydride in 25 cc. of propionicacetic acids (1:5), hereinafter referred to as 1:5 acid. The mineral acid was neutralized to Congo red with ammonium acetate and stirred without cooling for 2.5 hours. The mix was then drowned in 200 cc. of saturated salt solution. The dye was isolated by filtration, washing with ice water and drying at 60 C. The yield was 8 g. of a bright yellow solid. This product can be boiled in water without alteration. However, upon solution in 2% Na C solution and warming to 40 C. the color was permanently discharged in about 15 seconds.

Example 2 1.81 g. of S-aminoisophthalic acid were dissolved in 10 cc. of water and 3.3 cc. of concentrated HCl. After cooling to C., a solution of 0.72 g. NaNO in 5 cc. of water was added at 5-6 C. After 30 minutes at this temperature, the diazonium salt was added to a solution of 1.26 g. of B-methylglutaconic anhydride and 1.0 g. of sodium acetate (anhydrous) in 50 cc. of water and 25 g. of ice. After 15 minutes the dye was filtered off, washed with HO], and dried at room temperature. The yield was 2 g. of a substance behaving almost precisely as the product of Example 1.

Example 3 2.7 g. of 2-amino-5-toluenesulfonic acid were dissolved in 12.5 cc. of water and 1.25 g. KOH. After cooling to 5 C., a solution of 1.0 g. of NaNO: in 5 cc. of water was added. At 5 C. a solution of 2 cc. H 0 and 4 cc. concentrated HCl was added in about 10 minutes and the solid diazonium salt filtered ofi. The filter cake was added to a solution of 1.83 g. B-methylglutaconic anhydride in cc. of 1:5 acid at 5 C., neutralized to Congo red with ammonium acetate and stirred 2 hours without cooling. After isolation as in Example 1, there were obtained 4.9 g. yellow product, which behaved towards alkali precisely as did the product of Example 1.

Example 4 The product obtained by coupling p-nitroaniline to methylglutaconic anhydride was dissolved in tricresyl phosphate. The solution was dispersed in a gelatin solution and used as in Example 4. v

In a manner similar to that illustrated in the above examples, other filter dyes selected from those represented by Formulas II (or I) and HI above can be incorporated in photographic elements. In many cases, the light-screening dyes of my invention are discharged during photographic development. In those cases where this does not occur, the dye can be discharged by simply bathing the photographic element in a dilute alkaline solution for a few seconds as mentioned above. This treatment does not harm the photographic element in any way.

My invention an be further illustrated by reference to the accompanying drawing. As shown therein, Figure 1 is a sectional view of a multi-layer film in which the support 10 of any suitable material, such as cellulose acetate, paper, metal, polyvinyl acetal film, superpolyamide film, etc. is coated with gelatino-silver halide emulsion layers 11, 12 and 13, sensitive to the red, green, and blue regions of the spectrum, respectively. The layer 14 is a gelatin filter layer containing one of the filter dyes of my invention, such as that represented by Example 3 above.

Figure 2 illustrates another modification of my invention in which the support 10 is coated on one side with emulsion layer 16 and on the opposite side with gelatin layer 17 containing one of the filter dyes of my invention, such as the dye set forth in Example 3.

The light-sensitive salts which can be employed in my invention comprise the ordinary gelatino-silver-halide, such as gelatino-silver-chloride, gelatino-silver-bromide, gelatino-silver-chlorobromide, gelatino-silver-bromiodide, gelatinosilver-chlorobromiodide, etc. The light-sensitive a 6 layers can contain the usual sensitizing dyes, such as cyanine, merocyanine, etc., dyes. I

While various materials have been previously suggested for use as light-screening filters in photographic elements, no completely satisfactory one has been suggested as yet for this use, although the type of material which has been 'found to be most effective, in general, is a filter layer containing colloidal silver, known as Carey Lea. This silver layer has. various disadvantages, the first one being that it has appreciable green absorption, which leads to loss of effective speed in the magenta layer. Under some conditions, the particles of silver also act as nuclei for physical development which leads to deposition of dye in areas where it is not wanted. The filter layers of my invention do not possess any detectable green orred absorption, and they are rapidly and irreversibly bleached under the alkaline conditions used in color development, forming, for example, soluble and innocuous fragments.

. Instead of incorporating the azo dyes of my invention in a separate layer as pictured in the appended drawings, the light-screening filters of my invention can be incorporated in one of the light-sensitive layers. The lightscreening filter will then be easily removed during the usual photographic processing.

What I claim as my invention and desire secured by Letters Patent of the United States is:

1. A light-sensitive photographic element comprising light-sensitive silver halide and a light-absorbing, waterpermeable colloid layer containing a dye represented by the following general formula:

wherein R represents an aryl group.

3. A photographic element comprising at least one light-sensitive silver halide emulsion layer and a lightabsorbing, water-permeable colloid layer containing a dye selected from those represented by the following general formula:

wherein R represents a monocyclic aromatic group of the benzene series.

4. A photographic element comprising at least one light-sensitive silver halide emulsion layer and a lightabsorbing, water-permeable colloid layer containing a dye selected from those represented by the following general formula:

wherein R represents a monocyclic aromatic group of the benzene series having substituted thereon a radical selected from the group consisting of a carboxyl radical, a sulfo radical, and alkali metal salts of said radicals.

5. A photographic element comprising at least one light-sensitive silver halide emulsion layer and a lightabsorbing, water-permeable colloid layer containing a dye selected from those represented by the following general formula:

wherein R and R each represents a member selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group, a cyano group, a sulfonamido group, a hydroxyl group, an alkoxyl group, an aryloxyl group, an aryl group, an alkyl group, an alkanesulfonyl group, an arenesulfonyl group, a carbalkoxyl group, a carbamido group, and a guanidino salt of a sulfo group.

6. A photographic element comprising at least one light-sensitive silver halide emulsion layer and a lightabsorbing, water-permeable colloid layer containing a dye represented by the following formula:

8 7. A photographic element comprising at least one light-sensitive silver halide emulsion layer and a lightabsorbing, water-permeable colloid layer containing a dye represented by the following formula:

CH; CODE I H /C\ 8. A photographic element comprising at least one light-sensitive silver halide emulsion layer and a lightabsorbing, water-permeable colloid layer containing a dye represented by the following formula:

3 H HOaSQ-NN=C r m 0:1 o=0 References Cited in the file of this patent UNITED STATES PATENTS 2,390,707 Heimbach Dec. 11, 1945 2,432,419 Heimbach Dec. 9, 1947 2,461,485 Thompson Feb. 8, 1949 2,464,785 Thompson Mar. 22, 1949 2,704,711 Hanson Mar. 22, 1955 

1. A LIGHT-SENSITIVE PHOTO/GRAPGIC ELEMENT COMPRISING LIGHT-SENSITIVE SILVER HALIDE AND A LIGHT-ABSORBING, WATERPERMEABLE COLLOIDE LAYER CONTAINING A DYE REPRESENTDD BY THE FOLLWING GENERAL FORMULA: 